Add annotations

[Jebbs]

There are a couple of annotations that I would like to add including but not limited to:

nothrow
pure(where I can)
safe/trusted(maybe?)
nogc

[aubade]

FWIW, if i remember right, @safe actually changes some stuff during codegen in ways that can hurt performance. (Like forcing array bounds checks) In a multimedia library like this, it might be best to be judicious with that particular attribute.

[Jebbs]

That is good to know!

I'll ask around on the forums about some of those things before I pop into this, but it won't be for a while anyways since there are far more important things to do.

[Jebbs]

Final would be a good one to add too!